Comprehensive physical layer diagnostics capabilities are now an integrated standard in all of R. Stahl's ISbus fieldbus power supplies. Almost at no extra cost, these enable complete and consistent plant monitoring in Foundation fieldbus H1 segments. In addition to overload and short-circuit detection, continuous monitoring of all quality-relevant physical parameters of the fieldbus is ensured: voltage and current in the trunk, signal and noise levels, asymmetries and, in particular, jitter.The diagnostic functions can be used during installation, but also during operation. For troubleshooting. Each standard PC can read out the physical layer values via a serial interface on the front of the device without special drivers or DTMs. In the "Advanced" version of the module, additional alarm thresholds for detecting a deterioration of the transmission quality can be set individually. The message is issued via a potential-free relay contact as well as via colored LED displays in the traffic light look. For optional online access, an additional diagnosis communication module is available. Physical layer information from up to eight FF H1 bus segments can be cyclically transferred to asset management systems for enhanced analysis using Enhanced EDD support.